Retardation of fatigue crack growth in thin AA2024 sheets by laser heating

摘要

Local heating was applied by means of a defocussed laser beam with the aim of generating residual stress profiles with high compressive stresses perpendicular to the crack growth direction. The retardation effect on the fatigue crack growth behaviour was investigated for different heating line configurations. The corresponding experiments were carried out using M(T)200 specimens, fabricated out of sheets of the aluminium alloy 2024 T3 with a thickness of 2 mm. Constant stress amplitude fatigue crack growth tests at a R-ratio 0.1 were performed. One laser heating line on each side of the specimen results in an increase in fatigue lifetime of 10% in comparison to the base material. Each additional line further increases the number of load cycles until failure. Finally, with four lines on each side, a gain of approximately 425% in load cycles was reached.